Effervescence

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Bubbles of carbon dioxide float to the surface of a carbonated soft drink.

Effervescence is the escape of gas from an aqueous solution and the foaming or fizzing that results from a release of the gas.[1] The word effervescence is derived from the Latin verb fervere preceded by the adverb ex, which means to boil. It has the same linguistic root as the word fermentation, a complex biochemical reaction leading amongst others to the production of carbon dioxide and to the subsequent liberation of CO2 gas from the solution when this latter becomes supersaturated with respect to this gas. The making of beer, wine, or champagne, by fermentation is thus also accompanied by effervescence of CO2 from the barrel where the process occurs.

Effervescence can also be observed when opening a bottle of champagne, beer or carbonated beverages such as soft drinks. The visible bubbles are produced by the escape from solution of the dissolved gas (which itself is not visible in the liquid solution).

In the laboratory, a common example of effervescence is seen if hydrochloric acid is added to a block of limestone. If a few pieces of marble or an antacid tablet are put in hydrochloric acid in a test tube fitted with a bung, effervescence of carbon dioxide can be witnessed.

CaCO3 + 2 HCl → CaCl2 + H2O + CO2

This process is generally represented by the following reaction, where a pressurized dilute solution of carbonic acid in water releases gaseous carbon dioxide at decompression:

H2CO3 → H2O + CO2

In simple terms, it is the result of the chemical reaction occurring in the liquid which produces a gaseous product. [2]

See also

References

  1. ^ http://www.ktf-split.hr/glossary/en_o.php?def=effervescence
  2. ^ G. Liger-Belair et al., "Study of Effervescence in a Glass of Champagne: Frequencies of Bubble Formation, Growth Rates, and Velocities of Rising Bubbles", Am. J. Enol. Vitic. 50:3(1999)317-23 [1]